Lanthanide Borohydrides as Precursors to Organometallic Compounds. Mono(cyclooctatetraenyl) Neodymium Complexes

Guillaume, Sophie M.; Gland, Gildas Le; Nierlich, and Martine; Ephritikhine, Michel

doi:10.1021/om000558f

Cited by 134 publications

(143 citation statements)

References 57 publications

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“…Toluene soluble Ln(BH 4 ) 3 (THF) 3 are useful precursors for organolanthanides syntheses, alternatively to the traditional trichlorides [23][24][25]. Moreover, Ln(BH 4 ) 3 (THF) 3 allowed the formation and isolation of very scarce examples of early half-lanthanidocenes, which are generally not isolable in the case of chloro homologues, the latter easily undergoing comproportionation reactions [26].…”

Section: Synthesis and Characterization Of Cp* 2 Nd(bh 4 )(Thf) (1)mentioning

confidence: 99%

“…Despite the paramagnetism of neodymium, the 1 H NMR spectrum of 1 can be easily interpreted ( Figure 1 [24], respectively. The signals of THF in 1 are depicted at -11.7 and -34.9 ppm, a quite usual range for a molecule of THF that is coordinated to the neodymium atom [32].…”

Section: ((Equation 2))mentioning

confidence: 99%

“…In contrast, halide analogues often display an anionic, "ate" molecular structure [34], as exemplified by the wellknown Cp* 2 NdCl 2 Li(OEt 2 ) 2 [35]. A few examples of anionic bisborohydride metallocene-like complexes were described for the early series but they bear poor electron donating ligands [24,25].…”

Section: ((Equation 2))mentioning

confidence: 99%

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Synthesis and X-ray structure of a borohydrido metallocene of neodymium and its use as pre-catalyst in Nd/Mg dual-component ethylene and isoprene polymerisations

Visseaux

Chenal

Roussel

et al. 2006

Journal of Organometallic Chemistry

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Cp* 2 Nd(BH 4 )(THF) (1) (Cp* = C 5 Me 5 ) has been readily obtained in one step from Nd(BH 4 ) 3 (THF) 3 and fully characterized by 1 H NMR, IR spectroscopy, and elemental analysis. Its X-Ray structure displays a neutral monomeric complex, bearing one slightly distorted terminal BH 4group. Associated to nBuEtMg, 1 affords a highly active catalyst for ethylene polymerisation, the first one prepared from a borohydrido organolanthanide pre-catalyst. In the same experimental conditions, the catalytic behaviour of 1 is similar to that of previously described Cp* 2 NdCl 2 Li(Et 2 O) 2 (2). The 1/nBuEtMg system is not deactivated even in the presence of large excesses of THF. In contrast to its chloro homologue 2, the addition of 1 equivalent of nBuEtMg to 1 affords a catalyst for a trans-selective polymerisation of isoprene.2

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Section: Synthesis and Characterization Of Cp* 2 Nd(bh 4 )(Thf) (1)mentioning

confidence: 99%

Section: ((Equation 2))mentioning

confidence: 99%

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Synthesis and X-ray structure of a borohydrido metallocene of neodymium and its use as pre-catalyst in Nd/Mg dual-component ethylene and isoprene polymerisations

Visseaux

Chenal

Roussel

et al. 2006

Journal of Organometallic Chemistry

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“…The second part shows the effect on isoprene polymerisation of the addition of a NHC molecule to bisborohydrides Cp*Ln(BH 4 ) 2 (THF) n (Ln = Sc, n = 1, 1a; Nd, n = 2, 1b; Sm, n = 2, 1c) and to trisborohydrides Ln(BH 4 ) 3 (THF) n (Ln = Sc, n = 1.5, 2a; Nd, n = 3, 2b; Sm, n = 3, 2c) as pre-catalysts. Complex (L 33 We have been able to isolate X-ray quality crystals of this compound by recrystallization from THF-pentane mixtures and we resolved its molecular structure for the first time (Fig. 1) Polymerisation of isoprene with 1b/borate/Al( i Bu) 3 Factors that govern the selectivity in conjugated dienes polymerisation are closely connected to the coordination mode of the monomer to the catalyst (see Fig.…”

Section: Introductionmentioning

confidence: 99%

Tuning the catalytic properties of rare earth borohydrides for the polymerisation of isoprene

et al. 2013

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Previous results obtained for the cis-polymerisation of isoprene with scandium half-sandwich complex Cp*Sc(BH 4 ) 2 (THF) 1a were extended to its neodymium analog. The X-ray structure of the already reported neodymium monomer compound Cp*Nd(BH 4 ) 2 (THF) 2 1b is presented. Cp*Nd(BH 4 ) 2 (THF) 2 /[CPh 3 ]-[B(C 6 F 5 ) 4 ]/Al( i Bu) 3 catalytic system was found to be very active and stereoselective towards isoprene polymerisation, leading to highly 1,4-cis polyisoprene up to 92%. The effect on isoprene polymerisation of the addition of a NHC molecule to Cp*Ln(BH 4 ) 2 (THF) n pre-catalyst (Cp* = η 5 -C 5 Me 5 , Ln = Sc, n = 1, 1a; Nd, n = 2, 1b; Sm, n = 2, 1c) or to a trisborohydride Ln(BH 4 ) 3 (THF) n (Ln = Sc, n = 1.5, 2a; Nd, n = 3, 2b; Sm, n = 3, 2c) was also studied. Several NHC ligands were assessed: the classical [1-C{(N t BuCH)} 2 ] (L 1 ) and functional N-heterocyclic carbenes, two amino-tethered HNBu t CH 2 CH 2 [1-C{N(CHCH)NR}] (HL 2-R ) (R = t Bu, Mes (Mes = 2,4,6-Me 3 -C 6 H 2 )) and the hydroxyl-tethered HOCMe 2 CH 2 [1-C{N(CHCH)N i Pr}] (HL 3 ). Neodymiumbased complex (L 2-tBu )Nd(BH 4 ) 2 (THF) 2 3 could be isolated and characterized. With some of the catalytic combinations tested, the introduction of the NHC ligand in the coordination sphere of the complex induces a switch of the stereoselectivity of the resulting polymer. Scandium complex 2a, which produces mainly 1,4-cis polyisoprene when associated to a borate activator and aluminum alkyl, leads to 1,4-trans polymer up to 94% regular when HL 2-tBu carbene is added to the same reaction mixture. This result is the only example of highly trans-polyisoprene synthesized with a scandium based catalyst. Coordination of the carbene moiety to the rare earth centre is confirmed by NMR studies on paramagnetic neodymium pre-catalysts.

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“…Butadiene solution in toluene were purchased from Tokyo Chemical Industry Co. Ltd. (Tokyo, Japan) and used as received. Nd(BH 4 ) 3 (thf) 3 and Cp*Nd(BH 4 ) 2 (thf) 2 was prepared according to the literature and used immediately after the preparation [19]. Other materials were used without further purifications.…”

Section: Generalmentioning

confidence: 99%

Synthesis of Stereodiblock Polybutadiene Using Cp*Nd(BH4)2(thf)2 as a Catalyst

et al. 2017

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Butadiene polymerization, in both a highly cis-and trans-specific manner, was achieved by using a Cp*Nd(BH 4 ) 2 (thf) 2 -Bu 2 Mg system as an initiator. The cis-/trans-ratio can be tuned by the amount of trialkylaluminum-depleted modified methylaluminoxane (dMMAO). The cis-regularity of the polymer was much higher than those obtained by Nd(BH 4 ) 3 (thf) 3 . The molecular weight of cis-regular polymer was increased according to polymer yield, showing that there was no termination or chain transfer reaction during the polymerization. Synthesis of stereodiblock polybutadiene, which showed a high melting temperature (T m ) compared with stereodiblock polyisoprene, was also performed by the addition dMMAO during the polymerization.

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Lanthanide Borohydrides as Precursors to Organometallic Compounds. Mono(cyclooctatetraenyl) Neodymium Complexes

Abstract: International audienc

Cited by 134 publications

References 57 publications

Synthesis and X-ray structure of a borohydrido metallocene of neodymium and its use as pre-catalyst in Nd/Mg dual-component ethylene and isoprene polymerisations

Synthesis and X-ray structure of a borohydrido metallocene of neodymium and its use as pre-catalyst in Nd/Mg dual-component ethylene and isoprene polymerisations

Tuning the catalytic properties of rare earth borohydrides for the polymerisation of isoprene

Synthesis of Stereodiblock Polybutadiene Using Cp*Nd(BH4)2(thf)2 as a Catalyst

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